PE2950 SAS controller upgrade

[Tom Brown]

> Well, 1850 is a 1U unit, so it's really a tradeoff between having many disks 
> and having e.g. redundant fans and whatnot. I like thermally overdesigned 
> systems, and by keeping the component density reasonable, an 1850 has better 
> chances of surviving an AC failure in a server room etc. Unless you're 
> talking datacenter density, there's no reason not to use 2850 if you need 
> more disks IMHO. I'm a happy camper with a 2650 and 2850 in a small lab.

and a 1950 can now have 4 disks - which really is at the limit for 
density i'd say